The permanent alteration of the colour of keratinous fibres, in particular human hair, by the application of hair dyes is well known. In order to provide the consumer with the hair colour and the intensity of colour desired, a very complex chemical process is utilized. Permanent hair dyeing formulations typically comprise oxidative hair dye precursors, which can diffuse into the hair through the cuticle and into the cortex, where they can then react with each other and suitable oxidising agents to form the end dye molecules. Due to the larger size of these resultant molecules they are unable to readily diffuse out of the hair during subsequent washing with water and/or detergents; hence delivering the consumer-desired permanency of colour. This reaction typically takes place in an aggressive environment at approximately pH 10 in the presence of both an alkalizing agent and an oxidizing agent. In addition, preformed dyes may be used either instead of the oxidative hair dye precursors as a method to deliver colour or in combination with oxidative hair dye precursors. These preformed dyes are often intense and chromatic colours and can give the consumer the vibrant shades she desires. Moreover, the consumer repeats the hair dyeing process regularly in order to maintain the desired hair colour and shade and the intensity of colour and to ensure continual, even coverage of the hair including coverage of new hair growth.
The manufacturer of such products is also required to work within a large number of constraints. Since these products are being placed in direct contact with the consumers' skin, the potential exists for accidental contact with the eye or for ingestion (for example), which can occur during the dyeing process. Therefore, the formulations must meet rigorous safety requirements and not induce any allergic reactions. In addition, to meeting these requirements, the products must also be optically and olfactory pleasing to the consumer. In particular, the products need to meet certain physical parameters in order to ensure that the product can be easily applied to the hair by the consumer to provide the desired effect, without unintentional staining of the consumers' clothes, skin, particularly along the hair line, or other objects.
The manufacturer is also required to provide the hair colouring consumer with a large range of different resulting colours. Some consumers may just wish to enhance the natural colour of the hair, whilst others may wish to cover grey or completely alter the hair colour to a different natural appearing hair colour or a ‘synthetic’ appearing hair colour. Consequently, the manufacturer may provide over twenty different formulations, of varying colours and shades, to address the range of consumer specific needs. These formulations have to be individually formulated and are typically complex formulae containing a mixture of different dye compounds including oxidative and preformed dyes. As a result the manufacture of such product ranges can be costly and complex.
However, despite the fact that commercial hair dyeing products have been available for many years, the products still exhibit a number of consumer-related deficiencies. Typically permanent hair dye products will contain an alkali, typically a source of ammonia. This serves the purpose of swelling the hair, allowing the entry of the dye precursor molecules into the hair and also improves the lightening effect of the oxidising agent, which is typically hydrogen peroxide. However, ammonia is also volatile and its associated odour is extremely unpleasant to the consumers' of such products, particularly as these hair dye products are used in close proximity to the nasal region. Hence, it would be highly desirable to provide an oxidative hair colouring and/or bleaching composition which delivers the consumer required lightening level and colour, but which has reduced or eliminated the detectable ammonia odour.
In fact, another deficiency area in current hair colouring products is the provision of hair colouring products which deliver the required hair colour, especially the required lightening effect and grey hair coverage. The amount of grey hair to be coloured varies considerably from consumer to consumer. The resultant overall appearance of the coloured hair demanded by the consumer should be nearly identical for the naturally pigmented hair, the grey hair on head and new root growth so as to provide even colour deposition from root to tip. Furthermore it is also important that the initial uniform and even colour coverage is maintained during the post dyeing washing and drying cycle.
Delivering the required level of lightening is particularly important in order to provide the full range of colour shades demanded by the consumer, especially for blonde shades requiring yellow and golden tones and grey hair coverage. Such products pose particular difficulties to the manufacturer, as they usually require the use of high levels of oxidising agent and ammonia in order to deliver the required lightening effect. However, in addition to the problems associated with the presence of high levels of ammonia in these products, as discussed herein above, they also affect the condition of the hair and may in some cases induce mild skin irritation on the scalp. In particular, the hydrophilicity of the hair surface is increased during the colouring process, which alters the sensory perception of the hair and its overall manageability during and immediately after colouring, and during the subsequent wash and styling cycles until the next colourant application. Hence, it would also be highly desirable to provide an oxidative hair colouring and/or bleaching composition which delivers the required lightening and/or colour without unnecessary hair damage.
There is also a particular need to provide improved range of dyes which provide colour intensity, vibrancy and strength; typically associated with preformed dyes. However, the use of preformed dyes alone does suffer from restricted application dependant upon the consumers hair colour; for example, red shades are difficult to observe on hair which is dark brown. Consequently a lightening step is required. However preformed dyes are not sufficiently stable in typical oxidant systems, particularly with the persulphate/peroxide bleaches which are used to provide lightening highlights and blondes shades. As a consequence such dyes, if utilised, have to be delivered after the application of the bleaching step thus lengthening and complicating the process for the consumer. Moreover, all of the associated problems of the typical oxidant system are also introduced, such as malodour and fibre damage.
Another critical performance area for the consumer is the time that is required to fully develop the required colour. In particular, the application of hair dye products is still a relatively time consuming process and it may take the consumer over an hour to mix, apply, wait for the final colour to develop and remove the product; before drying and restyling. The majority of current colourant products take a minimum of at least 25 minutes for the final colour to fully develop such that the consumer has to sit with the product applied to the hair for this period of time. Preformed dye systems which deliver the dye rapidly to the hair are however also time consuming if a pre-lightneing step is required. Since for most consumers the hair dyeing process is a regular part of their beauty routine it would be highly desirable if the time required to dye the hair could be reduced whilst still meeting all of the other requirements of ease of application, low odour, and especially, of course, the delivery of the required hair colour, particularly for consumers requiring significant changes and/or levels of lift in the resultant colour.
There are a large number of dyes available which are used in hair colouring products. However, consumer demand for the delivery of specific colours is such that there is still a need to improve and increase the colours provided by hair colourant manufacturers. The development of new dyes however is extremely costly and time consuming and thus the number of new dyes available does not increase significantly over time.
Hence, it would be further desirable to provide the consumer with a hair colourant, providing improved lift and lightening, improved colour delivery, uptake and durability and which provide improved colour and colour variations based upon currently available dyes.
It has now been surprisingly found that hair colouring and/or bleaching systems comprising an oxidizing agent, a source of carbonate ions, an alkalising agent, and preformed dyes, as defined herein below, utilised at pH 9.5 and below, provide hair colouring and bleaching compositions which provide improved uniform root to tip colour delivery and deposition, improved intensity with the required lift and lightening, especially for blonde shades, and excellent grey coverage. Moreover, the compositions of the present invention also surprisingly exhibit low odour and deliver a high level of lift and lightening equal to the currently utilised ammonia/peroxide systems, whilst reducing the concentration of peroxide and reducing the hair fibre damage. The compositions further require less time for application and also deliver excellent wash fastness
A number of attempts have been described in the literature to address at least some of the above identified improvement areas. For example, the use of carbonate has been described in the following hair colouring art. However none of these references disclose the claimed features of the present invention.
EP 435 012 describes hair-dyeing compositions, which require a short dyeing time, create little damage to hair, and no irritating odour after dyeing, comprising a carbonate source, a non odour generating alkali hydrogen peroxide and a buffer solution. Similarly EP 1 106 166 describes hair dye compositions comprising ammonia, carbonate (other than ammonia salt), transition metal salt and chelating agent which do not give off an irritating odour, have low skin irritation and can change the hair colour into a lighter tone in a short time. WO01/28508 describes hair colouring formulations comprising oxidising agents and ammonia carbonate or carbamate which deliver improved bleaching and colouring with reduced odour and hair damage without the need for buffering agents, pH modifiers or hair swelling agents. JP01206825 describes a low pungent hair colouring composition comprising ammonia, ammonium salt and carbonate. US2004/0083557 describes hair colouring compositions comprising an oxidative hair dye precursor, a metal cyanate, an alkalizing agent and an oxidizing agent and preferably a metal bicarbonate salt in order to provide good colour lift and low odour.
WO04/014328 describes one step hair colouring compositions comprising peroxide oxidizing agents, specific oxidizing agents and at least one water soluble carbonate releasing salts which more effectively deliver colour wherein the composition is applied for a period of from 2 to 60 minutes. US2004/0098814 describes a method of permanently colouring hair whereby the hair is subjected to a number of consecutive short treatments whereby the treatment comprises a dye intermediate in a shampoo or conditioner base, a water soluble carbonate releasing salt and a water soluble ammonium salt. US2004/0098816 also describes a method for the gradual permanent colouring of hair which includes subjecting the hair to a number of treatments having a set time interval between them, wherein the treatment compositions comprise ammonium carbonate in combination with a chelant.